<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		div{
			width: 300px;
			height: 300px;
			/*background-color: transparent;*/
			/*background-color: red;*/
			/*background-color: #ff0000;*/
			background-color: rgb(255,0,0);
			/*padding: 10px;*/
			/*margin: 10px;*/
			border: 20px dashed;
		}
	</style>
</head>
<body>
	<div>background-color</div>
</body>
</html>